[fix lint warnings: NFTs pallet] fix clippy::missing_docs_in_private_items warnings (#14610)

* add docs for impl_codec_bitflags

* add missing docs for type aliases

* add docs to transfer module

* add docs for settings module

* add docs to roles module

* add docs to metadata module

* add docs to migration module

* add missing docs to feature library

* methods not functions

* add docs to lock module

* add docs to attributes module

* add docs to create_delete_item module

* add docs for create_delete_collection module

* add docs to buy_sell module

* add missing doc for buy_sell module

* add docs to atomic_swap module

* add docs to atomic_swap module

* add docs for approvals module

* run cargo fmt

* Fix issues with multi-line comments

* Apply suggestions from code review

Co-authored-by: Jegor Sidorenko <5252494+jsidorenko@users.noreply.github.com>

* update from review

* fmt

* update from review

* remove bitflag example

* ".git/.scripts/commands/fmt/fmt.sh"

* Apply suggestions from code review

Co-authored-by: Squirrel <gilescope@gmail.com>

* add note about pallet features

---------

Co-authored-by: Jegor Sidorenko <jegor@parity.io>
Co-authored-by: Jegor Sidorenko <5252494+jsidorenko@users.noreply.github.com>
Co-authored-by: parity-processbot <>
Co-authored-by: Squirrel <gilescope@gmail.com>

substrate/frame/nfts/src/features/settings.rs

@@ -15,10 +15,19 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//! This module provides helper methods to configure collection settings for the NFTs pallet.
+
 use crate::*;
 use frame_support::pallet_prelude::*;
 
 impl<T: Config<I>, I: 'static> Pallet<T, I> {
+	/// Forcefully change the configuration of a collection.
+	///
+	/// - `collection`: The ID of the collection for which to update the configuration.
+	/// - `config`: The new collection configuration to set.
+	///
+	/// This function allows for changing the configuration of a collection without any checks.
+	/// It updates the collection configuration and emits a `CollectionConfigChanged` event.
 	pub(crate) fn do_force_collection_config(
 		collection: T::CollectionId,
 		config: CollectionConfigFor<T, I>,
@@ -29,6 +38,22 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		Ok(())
 	}
 
+	/// Set the maximum supply for a collection.
+	///
+	/// - `maybe_check_owner`: An optional account ID used to check permissions.
+	/// - `collection`: The ID of the collection for which to set the maximum supply.
+	/// - `max_supply`: The new maximum supply to set for the collection.
+	///
+	/// This function checks if the setting `UnlockedMaxSupply` is enabled in the collection
+	/// configuration. If it is not enabled, it returns an `Error::MaxSupplyLocked`. If
+	/// `maybe_check_owner` is `Some(owner)`, it checks if the caller of the function is the
+	/// owner of the collection. If the caller is not the owner and the `maybe_check_owner`
+	/// parameter is provided, it returns an `Error::NoPermission`.
+	///
+	/// It also checks if the new maximum supply is greater than the current number of items in
+	/// the collection, and if not, it returns an `Error::MaxSupplyTooSmall`. If all checks pass,
+	/// it updates the collection configuration with the new maximum supply and emits a
+	/// `CollectionMaxSupplySet` event.
 	pub(crate) fn do_set_collection_max_supply(
 		maybe_check_owner: Option<T::AccountId>,
 		collection: T::CollectionId,
@@ -56,6 +81,18 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		})
 	}
 
+	/// Update the mint settings for a collection.
+	///
+	/// - `maybe_check_origin`: An optional account ID used to check issuer permissions.
+	/// - `collection`: The ID of the collection for which to update the mint settings.
+	/// - `mint_settings`: The new mint settings to set for the collection.
+	///
+	/// This function updates the mint settings for a collection. If `maybe_check_origin` is
+	/// `Some(origin)`, it checks if the caller of the function has the `CollectionRole::Issuer`
+	/// for the given collection. If the caller doesn't have the required permission and
+	/// `maybe_check_origin` is provided, it returns an `Error::NoPermission`. If all checks
+	/// pass, it updates the collection configuration with the new mint settings and emits a
+	/// `CollectionMintSettingsUpdated` event.
 	pub(crate) fn do_update_mint_settings(
 		maybe_check_origin: Option<T::AccountId>,
 		collection: T::CollectionId,
@@ -80,6 +117,13 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		})
 	}
 
+	/// Get the configuration for a specific collection.
+	///
+	/// - `collection_id`: The ID of the collection for which to retrieve the configuration.
+	///
+	/// This function attempts to fetch the configuration (`CollectionConfigFor`) associated
+	/// with the given `collection_id`. If the configuration exists, it returns `Ok(config)`,
+	/// otherwise, it returns a `DispatchError` with `Error::NoConfig`.
 	pub(crate) fn get_collection_config(
 		collection_id: &T::CollectionId,
 	) -> Result<CollectionConfigFor<T, I>, DispatchError> {
@@ -88,6 +132,14 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		Ok(config)
 	}
 
+	/// Get the configuration for a specific item within a collection.
+	///
+	/// - `collection_id`: The ID of the collection to which the item belongs.
+	/// - `item_id`: The ID of the item for which to retrieve the configuration.
+	///
+	/// This function attempts to fetch the configuration (`ItemConfig`) associated with the given
+	/// `collection_id` and `item_id`. If the configuration exists, it returns `Ok(config)`,
+	/// otherwise, it returns a `DispatchError` with `Error::UnknownItem`.
 	pub(crate) fn get_item_config(
 		collection_id: &T::CollectionId,
 		item_id: &T::ItemId,
@@ -97,6 +149,14 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		Ok(config)
 	}
 
+	/// Get the default item settings for a specific collection.
+	///
+	/// - `collection_id`: The ID of the collection for which to retrieve the default item settings.
+	///
+	/// This function fetches the `default_item_settings` from the collection configuration
+	/// associated with the given `collection_id`. If the collection configuration exists, it
+	/// returns `Ok(default_item_settings)`, otherwise, it returns a `DispatchError` with
+	/// `Error::NoConfig`.
 	pub(crate) fn get_default_item_settings(
 		collection_id: &T::CollectionId,
 	) -> Result<ItemSettings, DispatchError> {
@@ -104,6 +164,13 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		Ok(collection_config.mint_settings.default_item_settings)
 	}
 
+	/// Check if a specified pallet feature is enabled.
+	///
+	/// - `feature`: The feature to check.
+	///
+	/// This function checks if the given `feature` is enabled in the runtime using the
+	/// pallet's `T::Features::get()` function. It returns `true` if the feature is enabled,
+	/// otherwise it returns `false`.
 	pub(crate) fn is_pallet_feature_enabled(feature: PalletFeature) -> bool {
 		let features = T::Features::get();
 		return features.is_enabled(feature)